1. Field of the Invention
This invention relates to an electro-luminescence display (ELD), and more particularly to a method and apparatus for driving an electro-luminescence display panel that is capable of preventing an initial blinking phenomenon occurring at a power application.
2. Description of the Related Art
Recently, there have been highlighted various flat panel display devices reduced in weight and bulk that is capable of eliminating disadvantages of a cathode ray tube (CRT). Such flat panel display devices include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP) and an electro-luminescence (EL) display panel, etc.
The EL display panel of these display devices is a self-luminous device capable of light-emitting a phosphorous material by a re-combination of electrons with holes. The EL display panel is largely classified into an inorganic EL device using an inorganic compound as the phosphorous material and an organic EL device using an organic compound as it. Since such an EL display panel has many advantages of a low-voltage driving, a self-luminescence, a thin film type, a wide viewing angle, a fast response speed, and a high contrast, etc., it has been expected as a post-generation display device.
Generally, the organic EL device is comprised of an electron injection layer, an electron carrier layer, a light-emitting layer, a hole carrier layer and a hole injection layer that are sequentially disposed between a cathode and an anode. In such an organic EL device, if a desired voltage is applied between the cathode and the anode, electrons generated from the cathode are moved, via the electron injection layer and the electron carrier layer, into the light-emitting layer while holes generated from the anode are moved, via the hole injection layer and the hole carrier layer, into the light-emitting layer. Thus, the light-emitting layer emits a light by a re-combination of electrons and holes fed from the electron carrier layer and the hole carrier layer, respectively.
As shown in FIG. 1, an active matrix type EL display panel employing such an organic EL device includes a pixel matrix 20 having sub-pixels 28 arranged at each area defined by each intersection between gate lines GL and data lines DL, a gate driver 22 for driving the gate lines GL of the pixel matrix 20, a data driver 24 for driving the data lines DL of the pixel matrix 20, and a power supply 32 and a ground voltage source GND connected to the pixel matrix 20.
The gate driver 22 applies scanning pulses to sequentially drive the gate lines GL.
The data driver 24 supplies R, G and B data signals to each data line DL whenever the scanning pulse is applied. At this time, the data driver 24 converts digital data inputted from the exterior thereof into analog data signals. For instance, the data driver 24 voltage-divides a gamma reference voltage inputted from the exterior thereof into a plurality of gamma voltage levels, and selects the gamma voltage level corresponding to the input digital data to apply it as an analog data signal.
One pixel is implemented by a combination of the R, G and B sub-pixels 28. If the scanning pulse is applied to the gate line GL, then each of the R, G and B sub-pixels 28 receive a data signal from the data line DL to generate a light corresponding to the data signal. To this end, as shown in FIG. 2, each of the R, G and B sub-pixels 28 includes an EL cell OEL having a cathode connected to the ground voltage source GND, and a cell driver 30 connected to the gate line GL and the data line DL to control a current amount fed to an anode of the EL cell OEL from a power line PL, thereby driving the EL cell OEL.
The cell driver 30 includes a switching thin film transistor T1 having a gate terminal connected to the gate line GL, a source terminal connected to the data line DL and a drain terminal connected to a node N1, a driving thin film transistor T2 having a gate terminal connected to the node N1, a source terminal connected to the power line PL and a drain terminal connected to the EL cell OEL, and a storage capacitor C connected between the power line PL and the node N1.
If the scanning pulse is applied to the gate line GL, then the switching thin film transistor T1 is turned on to thereby apply a data signal supplied to the data line DL, via the node N1, to the gate terminal of the driving thin film transistor T2. At this time, the storage capacitor C charges a difference voltage between a driving voltage VDD supplied via the power line PL and the data signal supplied to the node N1. The driving thin film transistor T2 controls a current amount I fed from the power line PL to the EL cell OEL in response to a voltage supplied to the node N1, thereby controlling a light-emitting amount of the EL cell OEL. Further, when the switching thin film transistor T1 is turned off, the driving thin film transistor T2 supplies a constant current I until a data signal at the next frame is applied by a voltage charged in the storage capacitor C, thereby keeping a light-emission of the EL cell OEL.
In the conventional EL display panel having the above-mentioned configuration, as the power supply 32 is turned on, an initial driving voltage VDD is supplied to the pixel matrix 20 prior to an application of the data signal from the data driver 24. For this reason, since the EL cells OEL forms a current path by the initial driving voltage VDD suddenly supplied to the pixel matrix 20, there is raised a problem in that an initial blinking phenomenon occurs.